Phosphoenolpyruvate carboxykinase (GTP) (EC 4.1.1.32) (PEPCK) [1] catalyzes
the formation of phosphoenolpyruvate by decarboxylation of oxaloacetate while
hydrolyzing GTP, a rate limiting step in gluconeogenesis (the biosynthesis of
glucose). In vertebrates there are two isozymes: a cytosolic form whose
activity is affected by hormones regulating this metabolic process (such as
glucagon, or insulin) and a mitochondrial form.

An essential cysteine residue has been proposed [2] to be implicated in the
catalytic mechanism; this residue is located in the central part of PEPCK and
is in the center of a perfectly conserved region that we use as a signature
pattern.

Note:

Phosphoenolpyruvate carboxykinase (ATP) (EC 4.1.1.49) an enzyme that
catalyzes the same reaction, but using ATP instead of GTP, is not related to
the above enzyme (see <PDOC00460>).

Last update:

April 2006 / Pattern revised.

Technical section

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